Analog Devices VisualDSP++ 5.0 Service Manual page 47

For example, the DMA manager does not need control over all DMA
channels. The system can be configured for the DMA manager to control
some channels, leaving the application or other software to control other
DMA channels. (See the individual service chapters for more information
on each service.) There are, however, dependencies within the services of
which the application developer should be aware.
All current services, except the EBIU service, invoke the interrupt control
service for the management of interrupt processing. The DMA manager,
deferred callback, and power management services each depend on the
interrupt control service to manage interrupt processing for them.
If directed by the application to adjust SDRAM timing automatically, the
power management service uses the EBIU control service to affect
SDRAM timing parameter changes when the power/operating speed
profile of the processor is changed.
When configured to use deferred callbacks (as opposed to live or
interrupt-time callbacks) the DMA manager leverages the capabilities of
the deferred callback service to provide deferred callbacks to the applica-
tion. However, when configured for live callbacks, the DMA manager
does not use the deferred callback service.
The development toolset automatically determines these dependencies
and links into the executable only those services that are required by the
application. Because each service is built as its own object file within the
system services library file, you can further reduce the code size of the final
executable by commanding the linker to eliminate unused objects. Refer
to the development toolset documentation for more information.
VisualDSP++ 5.0 Device Drivers and System
Services Manual for Blackfin Processors
Introduction
1-9